Generate v4 (random) or v1 (time‑based) UUIDs
crypto.randomUUID() if available.
Founder & CEO, Toolraxy
Faiq Ur Rahman is a web designer, digital product developer, and founder of Toolraxy, a growing platform of web-based calculators and utility tools. He specializes in building structured, user-friendly tools focused on health, finance, productivity, and everyday problem-solving.
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This is a browser-based utility that generates Universally Unique Identifiers (UUIDs) according to RFC 4122 standards. It supports both UUID v4 (randomly generated) and UUID v1 (time-based) formats. You can generate between 1 and 20 UUIDs at a time, choose from multiple output formats (standard, no hyphens, or braced), and copy all results to your clipboard with one click. It’s an essential tool for developers working with databases, APIs, distributed systems, or any application requiring unique identifiers.
UUIDs are a fundamental building block in modern software development. They provide a way to generate unique identifiers without a central coordinating authority, making them ideal for distributed systems, database primary keys, and API resource identifiers. However, implementing RFC-compliant UUID generation correctly requires understanding bit layouts, version numbers, and variant bits. This tool eliminates that complexity, giving developers a reliable, standards-compliant source of UUIDs in seconds. Whether you need a single UUID for a quick test or a batch for database population, this tool delivers.
Using the UUID generator is straightforward:
Choose UUID Version:
Click “UUID v4 (Random)” for randomly generated UUIDs (most common).
Click “UUID v1 (Time)” for time-based UUIDs (include timestamp information).
Configure Settings:
Number of UUIDs: Enter a value between 1 and 20, or use the preset buttons (1, 5, 10) for quick selection.
Format: Select your preferred output format:
Standard – The classic format with hyphens: xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx
No hyphens – A continuous 32-character hex string: xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
Braced – Standard format wrapped in curly braces: {xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx}
Generate: Click the green Generate button. Your UUIDs will appear in the results panel.
Copy: Click “Copy All” to copy all generated UUIDs to your clipboard, formatted as a numbered list.
UUIDs are 128-bit numbers formatted as 32 hexadecimal characters, typically displayed in 5 groups separated by hyphens.
UUID v4 (Random): This version generates 122 random bits. The remaining 6 bits are used to indicate the version (4) and variant (RFC 4122). With 122 random bits, the probability of collision is astronomically low—you could generate billions of UUIDs every second for centuries without a duplicate. Modern browsers use the cryptographically secure crypto.randomUUID() method for true randomness.
UUID v1 (Time-based): This version combines a 60-bit timestamp (representing 100-nanosecond intervals since October 15, 1582), a 14-bit clock sequence (to handle clock rollbacks), and a 48-bit node identifier (usually the MAC address). Our tool simulates the timestamp using your computer’s clock and generates random values for the clock sequence and node, setting the appropriate version and variant bits to maintain RFC compliance.
Imagine you’re a developer building a RESTful API for a new e-commerce platform. You need to generate unique IDs for products, orders, and customers.
You open the UUID Generator and select UUID v4 for maximum randomness.
You set the number to 10 and click Generate.
You get ten UUIDs like:
1. 550e8400-e29b-41d4-a716-446655440000 2. 6ba7b810-9dad-11d1-80b4-00c04fd430c8 ...
You click “Copy All” and paste them directly into your database seed script.
Later, for logging purposes, you need time-ordered UUIDs. You switch to UUID v1, generate a batch, and use them as log entry identifiers. The timestamps embedded in the v1 UUIDs help with chronological sorting.
Dual Version Support: Both v4 (random) and v1 (time-based) UUIDs in one tool.
Multiple Output Formats: Standard, no-hyphen, and braced options for different use cases.
Batch Generation: Generate up to 20 UUIDs at once.
One-Click Copy: Copy all generated UUIDs to clipboard instantly.
RFC 4122 Compliant: All UUIDs follow the official standard.
Modern Browser Support: Uses crypto.randomUUID() where available for true randomness.
Fallback Support: Works on all browsers, including older ones.
No Installation: Runs entirely in your browser; no downloads or sign-ups.
Software Developers: For generating primary keys, API IDs, and unique tokens.
Database Administrators: For creating unique identifiers in database schemas.
System Architects: For designing distributed systems requiring unique IDs.
QA Engineers: For generating test data with realistic UUIDs.
Students: Learning about UUIDs and unique identifier generation.
Technical Writers: Creating documentation with example UUIDs.
Using v1 When v4 is More Appropriate: v1 UUIDs expose timestamp information and are predictable. Use v4 for security-sensitive contexts like session tokens or user IDs.
Exceeding 20 UUIDs: The tool limits batch size to 20 for readability. For bulk generation, generate multiple batches.
Assuming Global Uniqueness for v1: Our v1 simulation doesn’t use a real MAC address, so v1 UUIDs generated on different devices might collide. For distributed uniqueness, use v4.
Forgetting to Copy Before Regenerating: When you click Generate again, the previous UUIDs are replaced. Copy them first if you need to keep them.
The v1 UUID implementation in this tool is a simulation. It does not access your device’s MAC address (browsers cannot access this information for security reasons). Instead, it generates a random 48-bit node identifier with the multicast bit set, as recommended by RFC 4122 for software-based implementations. This means v1 UUIDs generated here are not guaranteed to be globally unique across different devices. For true time-based UUIDs with unique node identifiers, a server-side implementation with access to MAC addresses is required.
A Universally Unique Identifier (UUID) is a 128-bit number used to uniquely identify information in computer systems. The term “globally unique identifier” (GUID) is also used, typically in Microsoft systems. UUIDs are standardized by the Open Software Foundation (OSF) as part of the Distributed Computing Environment (DCE). Their key advantage is that they can be generated independently without a central registration authority, making them perfect for distributed systems, database keys, and scenarios where coordination between generating parties is impossible or impractical.
RFC 4122 defines five versions of UUIDs, each with a different generation method:
Version 1 (Time-based): Combines timestamp, clock sequence, and node (usually MAC address).
Version 2 (DCE Security): Similar to v1 but includes POSIX UID/GID (rarely used).
Version 3 (Name-based, MD5): Generated by hashing a namespace and name with MD5.
Version 4 (Random): Generated from random or pseudo-random numbers (most common).
Version 5 (Name-based, SHA-1): Similar to v3 but uses SHA-1 instead of MD5.
The variant field (bits 64-65 of the UUID) indicates the layout and interpretation. RFC 4122 defines variant 1 (bits 10) as the standard. Our tool generates UUIDs with the correct version and variant bits automatically.
Not all UUIDs are equal from a security perspective.
UUID v4 is preferred for security-sensitive applications because its randomness makes it unpredictable. Session tokens, API keys, and user identifiers should use v4.
UUID v1 includes a timestamp, which can leak information about when an identifier was created. In some contexts, this could be a privacy or security concern. Additionally, if the node ID is a real MAC address, it could potentially identify the machine that generated the UUID.
For cryptographic applications, ensure your v4 UUIDs are generated with a cryptographically secure random number generator (like crypto.randomUUID()), not Math.random().
Using UUIDs as primary keys in databases has both advantages and drawbacks:
Advantages: Uniqueness across tables, databases, and servers; no need for central sequence generation; good for distributed systems.
Drawbacks: UUIDs are larger than integers (16 bytes vs. 4-8 bytes), which increases index size and can impact performance. The randomness of v4 UUIDs can cause index fragmentation because new values are not sequential.
Solutions: Some databases offer UUID-specific data types (like PostgreSQL’s uuid type). For time-ordered UUIDs, consider using v1 or “sequential UUID” variants (like v7, a newer draft standard) to improve index performance.
UUID v4 is randomly generated, making it ideal for security-sensitive applications and situations where unpredictability matters. UUID v1 is time-based and includes a timestamp, making UUIDs sortable chronologically but potentially predictable. Use v4 for most applications, and v1 when you need time-ordered identifiers.
Yes. Both v4 and v1 implementations follow the RFC 4122 standard, including correct version bits (4 for v4, 1 for v1) and variant bits (10 for RFC 4122).
The tool allows up to 20 UUIDs per batch to keep the display manageable. You can generate multiple batches if you need more.
Some systems, databases, or programming contexts prefer UUIDs as continuous 32-character strings without hyphens. The “no hyphens” format provides this compact representation.
The braced format wraps the standard UUID in curly braces (e.g., {550e8400-e29b-41d4-a716-446655440000}). This format is used in some programming languages and systems, such as Microsoft’s GUID representation in C#.
Yes, especially the v4 UUIDs generated via crypto.randomUUID() (in modern browsers) are cryptographically strong and suitable for production use. The fallback v4 implementation uses Math.random(), which is less secure; for production security needs, ensure you’re using a browser with crypto.randomUUID() support.
No. All UUID generation happens locally in your browser. We do not store, log, or transmit any of the identifiers you create. Your data stays completely private.
Astronomically low. With 122 random bits, you would need to generate about 2.71 quintillion UUIDs to have a 50% chance of a single collision. For practical purposes, v4 UUIDs are considered unique.
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